It is conventional practice in systems for recovering refrigerant from equipment under service, and in other refrigerant handling systems, to employ a refrigerant compressor having an inlet that receives refrigerant through flow controls, an evaporator/accumulator and oil separator, and an outlet connected through a compressor oil separator and a condenser to the refrigerant destination, such as a storage container. U.S. Pat. Nos. 4,261,178, 4,768,347, 5,211,024 and 5,261,249, all assigned to the assignee hereof, illustrate technology of this character. A general object of the present invention is to provide a refrigerant handling system for receiving refrigerant from a source in either liquid or vapor phase, and pumping such refrigerant to an outlet for connection to a storage container or the like, in which the refrigerant compressor is eliminated, along with attendant problems associated with lubricants and moving part wear, and in which the oil separation and refrigerant pumping functions are accomplished by simplified and economical hardware. Another object of the present invention is to provide a refrigerant handling system of the subject character that is quiet in operation, and that provides reliable service over an extended operating life. A further object of the present invention is to provide a refrigerant handling system in which little or no heat is transferred to the atmosphere, and is therefore not limited by ambient temperature.
A thermoelectric refrigerant handling system in accordance with the presently preferred embodiments of the invention includes a chamber having an inlet path for receiving refrigerant from a source thereof and an outlet for delivering refrigerant in vapor phase. A thermoelectric element is operatively disposed between the chamber and the refrigerant inlet path, and is responsive to application of electrical energy for transferring heat from the inlet path to the chamber. In this way, heat is withdrawn from refrigerant at the inlet path and refrigerant is drawn into the inlet from the source, while heat is added to refrigerant in the chamber until the refrigerant is vaporized and driven by vapor pressure through the chamber outlet. A controller applies electrical energy to the thermoelectric element for transferring heat energy into the chamber to vaporize the refrigerant contained therein until the chamber is substantially empty of refrigerant, and then opens a valve to feed refrigerant from the inlet path to the chamber. In this way, refrigerant is drawn from the source through the inlet, and effectively pumped in vapor phase through the outlet of the chamber.
The system inlet path in the preferred embodiments of the invention includes a second chamber, with the thermoelectric element being operatively disposed for transferring heat energy between the chambers. In one embodiment, the inlet valve feeds refrigerant to the second chamber, and a second valve selectively feeds refrigerant from the second chamber to the first chamber. In a second embodiment, the thermoelectric element is bidirectional, being responsive to electrical energy of one state or polarity for transferring heat from the second chamber to the first, and responsive to electrical energy of another state or polarity for transferring heat energy from the first chamber to the second. The inlet valve is connected for selectively and alternating feeding inlet refrigerant to the first and second chambers, and both of the chambers have an outlet for delivering refrigerant in vapor phase. The controller operates the inlet valve in a first mode of operation to feed refrigerant to the second chamber while applying electrical energy of the one state to the thermoelectric element for withdrawing heat from refrigerant in the second chamber while vaporizing refrigerant in the first chamber until the first chamber is substantially empty of refrigerant. The controller then operates the valve in a second mode of operation to feed refrigerant from the source to the first chamber while applying electrical energy at the other state to the thermoelectric element for withdrawing heat from refrigerant in the first chamber while vaporizing refrigerant in the second chamber until the second chamber is substantially empty of refrigerant. The first and second modes of operation are repeated alternately and in sequence, such that refrigerant is pumped through the first and second chambers in parallel from the inlet to the vapor outlets of the chambers. Check valves are disposed at the vapor outlets of the chambers to prevent reverse flow of refrigerant vapor when the associated chamber is being cooled.
The refrigerant inlet control in the preferred embodiments of the invention includes a liquid refrigerant level sensor for closing the inlet valve and thereby limiting admission of refrigerant so as not to exceed capacity of the system. The chamber or chambers in which refrigerant is vaporized also have a sensor for detecting when the chamber is substantially empty of refrigerant.